Alloy and manufactures



Patented Aug. 9, 1938 UNITED STATES ALLOY AND MANUFACTURES Vsevolod Nicholas Krivobok, Pittsburgh, Pa., as-

signor, by'mesne assignments, to Rustless Iron and Steel. Corporation, Baltimore, Md, a corporation of Delaware No Drawing. Application June 25, 1935, Serial This invention relates to chromium-nickel alloy-irons and steels and to articles and manufactures of the same.

Among the objects of my invention is the production of chromium-nickel alloy irons and steels which are strong, tough, durable and which are readily workable, asby forging and rolling into plates, bars, sheet, strip, rods and wire, which may be further machined, worked or formed, as by drilling, cutting, turning and bending, which may be welded where desired, to achieve a great number of products, articles or manufactures, such as tubing and piping, fluid valves, flanges and bolts, pans, vats and tanks, all for high temperature duty, as in stills, evaporator units and the like, for semi-chemical uses in the canning, dairy, oil and photographic film industries, or in chemical calciners used in the production of paints and dyes, or for valves, valve seats, exhaust manifolds, stacks and the like, as in internal combustion engines, or for buckets, nozzles and like parts for gas turbines or like articles, products or manufactures for high temperature service applications.

The invention accordingly consists in the combination of elements, composition of ingredients and mixture of materials, and in the articles, products and manufactures of the same, as described herein, the scope of the application of which is indicated in the following claims.

As conducive to a clearer understanding of certain features of my invention it may be noted at this point that the austenitic chromium-nickel irons and steels (irons and steels containing approximately, to 25% chromium, 7% to nickel, and the balance substantially iron) are used in the production of a wide variety of corrosion-resistant and mildly heat-resistant products or articles of manufacture. Thus, these austenitic irons and steels, especially the 18-8 ironsand steels (irons and steels containing 18% chromiuni, 8% nickel, and the balance substantially iron) may be used in a number of interior or exterior architectural applications, such as decorative trim, ornamentation and fixtures. Likewise, these irons and steels may be employed for a variety of kitchen, soda fountain, dairy and hospital applications, as in cooking and serving utensils, containers and appliances, counter and furniture trim and the like, where permanently bright corrosion-resistant metal capable of withstanding the corrosive action of various fruit and vegetable acids, is desired. Similarly, these irons and steels are widely adapted for various chemical plant apparatus and equipment where metal resistant to the corrosive attack of acids, alkalies and salts at room temperature, or slightly elevated temperatures, is required;

These austenitic chromium-nickel irons and steels, however, are not satisfactorilyadaptable to extremely high temperature duty, especially high temperature duty under strongly oxidizing or corrosive conditions, largely because of the susceptibility of these irons and steels to intergranular corrosion and because of their tending to flow at high temperatures.

.One of the outstanding objects of my inventionis the production of strong, tough and ductile alloy irons and steels, which may be readily worked or formedinto a variety of products, articles or manufactures, which are resistant to scaling, pitting and intergran'ular corrosion, at high temperatures over long periods of continuous operation under a variety of corrosive or corrosion-fostering media and under the many varying conditions encountered in actual, practical use. 1

Referring now more particularly to the practice of my invention, alloy iron or s eel analyzing approximately, 18% chromium, 8% nickel, 2.5% to 3.5% tungsten, 1% to 2% molybdenum, .07% to .1 carbon, and the balance substantially iron, with the usual percentages of silicon, manganese, sulphur and phosphorus, is conveniently produced in an electric furnace in a suitable manner, as for example, as described in Patent No. 1,925,182 granted to Alexander L. Feild September 5, 1933, and entitled Process for the manufacture of rustless iron. The alloy iron or steel of desired analysis is poured into suitable ingot molds where it is permitted to cool. The formed ingots are stripped from the molds and fashioned into blooms or billets in accordance with known methods and conveniently converted by hotworking methods or a combination of hot and cold methods into plate, sheet, strip, bars, rods or wire of desired dimensions. When desired the converted products are annealed to relieve working strains and then'cooled all in accordance with known methods. The cold-rolled sheet and strip, however, is preferably used without benefit of annealing treatment in order to gain full realization of the strength, hardness and 7 other superior physical characteristics imparted by the cold-working operations.

My alloy iron or steel is essentially austenitic in structure but contains certain new constituents in the form of complex ferrites and carbides lending to the metal superior working, corrosion-resisting and physical characteristics. The

-meal is corrosion-resistant and heat-resistant,

granular corrosion, grain growth, fatigue or failure. For example, a bar of austenitic chromiumresistance in use.)

nickel iron'analysing approximately, 18% chromium, 8% nickel, 3% tungsten, 2% molybdenum,

% carbon, and the balance substantially iron,

operations either from sheet, strip or bar stock.

The metal may be forged, upset or drawn,- it may be hot or cold rolled into sheet, strip and bar stock, which may be further worked or formed, as by bending, punching or blanking and may be machined by drilling, cutting, threading or the like, followed by welding where desired, either with the oxy-acetylene torch or with the electric are (preferably employing welding rods of approximately the same analysis as the stock welded) to achieve a great many articles, prodnets and manufactures. '(The various welded articles, products and manufactures are preferably given a stabilizing heat-treatment in accordance with well known methods to establish a stabilized condition of the metal after the welding is completed in order to assure minimum intergranular corrosion and maximum corrosion- For example, the bar, sheet and strip worked or formed as above indicated is fashioned into fluid valves, couplings, flanges and bolts, tanks,.trays and pans, all for high temperature duty as in boilers, condenseraoil .crackingstills, evaporator units and the like, or

for semi-chemical uses in the canning, dairy, oil and'photographic film industries, or chemical calciners, as used in the production of iron-free chemicals, such as paints and dyes. 1

Likewise, my chromium-nickel alloy iron or steel stock may be worked or formed, as above indicated, achieving a further variety of high temperature duty parts and accessories, such as internal combustion engine valves, valve seats,

exhaust manifolds andstacks, as used in the automotive and I aviation industries, ":or gas turbine buckets, noasles and like parts requiring strength, toughness, resistance to corrosion and scaling and resistance to impact and fatigue under the many V rying conditions of high temperature duty.

Thus, it will be seen that there is provided in' this invention a chromium-nickel alloy iron or steel and articles, products and manufactures of the min which the various objects hereinbeore noted, together with many thoroughly practical advantages are successfully achieved. It will beseen that the. alloy is strong, tough, corrodeo-resistant and heat-resistant and that it readily lends itself to a variety of working or forming operations into a number of commercial articles, products or manufactures, many of which are set forth above, which are pe ially adapted to withstand continuous high temperature duty over long periods of time and under the many "will! conditions of actual, practical use.

While as illustrative of my invention an austenitic chromium-nickel iron containing approximately. 18% chromium, 8% nickel, 2.5% to 3.5%

tungsten. 1% to 2% molybdenum, .0'I% to .1%

carbon, and the-balance substantially iron, is

about .7% up to about 3%. Likewise, good high temperature duty characteristics are achieved in modified chromium-nickel alloy irons and steels where the carbon content ranges between- .03% and .2%. The chromium-nickel irons and steels of the higher chromium and nickel contents, and ordinarily of the higher carbon contents, are especially employed in the production of a variety of cast articles or manufactures such as furnace parts, ore treating and handling apparatus, high temperature conveyor parts and equipment and like parts and machinery subjected to corrosive and abrasive conditions-as well as impact and shock in operation at high temperatures.

Certain further beneilts in long-life alloy iron and steel at unusually high operating temperatures are achieved by adding to the tungstenmolybdenum-chromium-nickel alloy iron or steel, the further ingredient, manganese, in the amount of from about.5% to 3%. High temper a'tur'e duty irons and steels of this analysis are especially resistant to the corrosive attack of sulphur-bearing gases at high temperatures and are of somewhat improvedworkability over the high temperature irons and steels indicated above.

As many possible embodiments may be made of my invention and as many changes may be made in the embodiment hereinbefore set forth, it is to be understood that all matter described herein is to be interpreted as illustrative, and not in a limiting sense.

I claim: I

1. In manufactures of the class described, alloy iron or steel articles substantially of austenitlc structure for use under high temperature conditions of stress, said articles comprising as ingredients, 10 per cent to 25 percent chromium. '1 per cent to per cent nickel, 2.1 per cent to 4 per cent tungsen, .7 per cent to 3 per cent molybdenum, .03 per cent to .2 per cent carbon. and the balance consisting of iron.

2. In manufactures of the class described, alloy iron or steel articles'substantially of austenitic structure for use under high temperature conditions of stress, said articles comprising as ingredients approximately, 18 per cent chromium. 8 per cent nickel, 2.5 per cent to 3.5 per cent tungsten, 1 per cent to 2 per cent molybdenum,

.07 per cent to .1 per cent carbon, and the balance consisting of iron. 5

3. In manufactures of theclass described, alloy iron or steel articles substantially of austenitic structure for use under high temperature conditions of stress, said articles comprising as ingredients approximately, 10 per cent to 25 per cent chromium, 7 per cent to 15 per cent nickel, 2.5 per cent to 3.5 per cent tungsten, 1 per cent to 2 per, cent molybdenum, .5 percent to 3 per cent manganese, .03 per cent to .2 per cent carbon, and the balance consisting of iron.

" VSEYOLOD. NICHOLAS KRIVOBOK. 

